York YCUL0016 - Manual (Page 9)

YORK INTERNATIONAL 8 YORK INTERNATIONAL 9
FORM 150.63-EG1
Selection Data
The ratings shown on pages 18 through 57 are based
on unit operation in a well designed and properly piped
system.
SELECTION RULES
1. Capabilities are based on Refrigerant 22 or 407C.
2. Ratings may interpolated, but must not be extrapo-
lated.
3. Ratings shown are at saturated suction temperatures
corresponding to pressures at the compressor. In
actual practice, suction line pressure drop has the
effect of reducing compressor capacity, forcing the
compressor to operate at a lower suction pressure to
maintain the desired evaporator temperature.
For normal air conditioning applications, size the
suction line for a pressure drop of 3 PSI, corresponding
to 2°F, for R-22 refrigerant. Thus, the evaporator
temperature will be approximately 2°F higher than the
compressor suction temperature. Line loss must be
taken into consideration when selecting the evapora-
tor.
SELECTION PROCEDURE
The air-cooled condensing unit may be selected from
the Ratings on pages 20 through 48, if the ambient air
temperature at the condenser and the saturated suction
temperature at the compressor are known. The ambi-
ent air temperature is a known design parameter, but
the suction temperature at the compressor, in many
cases, is known only within certain allowable limits.
The actual compressor operating suction temperature
and the overall performance of the system will depend
directly upon the choice of the evaporator. Starting with a
preliminary evaporator selection at a nominal evaporator
temperature and using data supplied by the evaporator
manufacturer, enter the ratings tables and select a unit to
meet the required cooling load at a suction temperature
at least 2°F below the evaporator temperature. The 2°F
allows for normal suction line loss.
If more accurate selection is required, the evaporator
capacity should be plotted against the condensing
unit capacity to determine the balanced system
performance. Again, it is necessary to factor in the
suction line loss.
After the system balance point has been determined,
the compressor KW input may be interpolated from
the ratings tables.
SAMPLE SELECTION
Select an R-22 Air-Cooled Condensing Unit with a
matched central station air handling unit having the
following operating conditions:
Design Conditions
1. An air handling unit with four large DX coils (two
per circuit) having a total cooling load of 600 MBH
(50 tons).
2. The coil suction temperature required 45°F.
3. The design outdoor ambient temperature is 90°F.
4. The power supply is 460V/3 phase/60 HZ.
Selection
1. Enter the YCUL 60 HZ Rating Table (page 20).
2. The model YCUL0056EC will provide 51.3 tons with
48.3 compressor KW input at 90°F ambient air and
43°F suction pressure.
3. Calculate the compressor KW input for the specific
design conditions of 50 tons and 90°F ambient air.
KW =
50tons
x 48.3 KW = 47.1 KW 51.3 tons
The YCUL0056EC is the suitable selection for the design
capacity.